A bowl contains w white balls and b black balls. One ball is selected at random from the bowl, its color noted, and is returned to the bowl along with n additonal balls of the same color. Another ball is randomly selected (now containing w + b + n balls) and is observed black. Show that the conditional probability is w/w+b+n.

Oct 1st 2009, 07:22 AM

Plato

Quote:

Originally Posted by vexiked

A bowl contains w white balls and b black balls. One ball is selected at random from the bowl, its color noted, and is returned to the bowl along with n additonal balls of the same color. Another ball is randomly selected (now containing w + b + n balls) and is observed black. Show that the conditional probability is w/w+b+n.

Again, I suspect no one is quite sure what this question means.
Read this. “Show that the conditional probability is w/w+b+n”
Does that make any sense to you?
“the conditional probability” of what?

Oct 1st 2009, 07:29 AM

vexiked

The problem should state:

A bowl contains w white balls and b black balls. One ball is selected at random from the bowl, its color noted, and is returned to the bowl along with n additonal balls of the same color. Another ball is randomly selected (now containing w + b + n balls) and is observed black. Show that the conditional probability that the first ball selected was white is w/w+b+n.

Oct 1st 2009, 07:54 AM

Plato

Quote:

Originally Posted by vexiked

A bowl contains w white balls and b black balls. One ball is selected at random from the bowl, its color noted, and is returned to the bowl along with n additonal balls of the same color. Another ball is randomly selected (now containing w + b + n balls) and is observed black. Show that the conditional probability that the first ball selected was white is w/w+b+n.